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(* *********************************************************************)
(* *)
(* The Compcert verified compiler *)
(* *)
(* Xavier Leroy, INRIA Paris-Rocquencourt *)
(* *)
(* Copyright Institut National de Recherche en Informatique et en *)
(* Automatique. All rights reserved. This file is distributed *)
(* under the terms of the INRIA Non-Commercial License Agreement. *)
(* *)
(* *********************************************************************)
(* Type inference for RTL *)
open Datatypes
open Camlcoq
open Maps
open AST
open Op
open Registers
open RTL
exception Type_error of string
let env = ref (PTree.empty : typ PTree.t)
let set_type r ty =
match PTree.get r !env with
| None -> env := PTree.set r ty !env
| Some ty' -> if ty <> ty' then raise (Type_error "type mismatch")
let rec set_types rl tyl =
match rl, tyl with
| [], [] -> ()
| r1 :: rs, ty1 :: tys -> set_type r1 ty1; set_types rs tys
| _, _ -> raise (Type_error "arity mismatch")
(* First pass: process constraints of the form typeof(r) = ty *)
let type_instr retty (Coq_pair(pc, i)) =
match i with
| Inop(_) ->
()
| Iop(Omove, _, _, _) ->
()
| Iop(op, args, res, _) ->
let (Coq_pair(targs, tres)) = type_of_operation op in
set_types args targs; set_type res tres
| Iload(chunk, addr, args, dst, _) ->
set_types args (type_of_addressing addr);
set_type dst (type_of_chunk chunk)
| Istore(chunk, addr, args, src, _) ->
set_types args (type_of_addressing addr);
set_type src (type_of_chunk chunk)
| Icall(sg, ros, args, res, _) ->
begin try
begin match ros with
| Coq_inl r -> set_type r Tint
| Coq_inr _ -> ()
end;
set_types args sg.sig_args;
set_type res (match sg.sig_res with None -> Tint | Some ty -> ty)
with Type_error msg ->
let name =
match ros with
| Coq_inl _ -> "<reg>"
| Coq_inr id -> extern_atom id in
raise(Type_error (Printf.sprintf "type mismatch in Icall(%s): %s"
name msg))
end
| Itailcall(sg, ros, args) ->
begin try
begin match ros with
| Coq_inl r -> set_type r Tint
| Coq_inr _ -> ()
end;
set_types args sg.sig_args;
if sg.sig_res <> retty then
raise (Type_error "mismatch on return type")
with Type_error msg ->
let name =
match ros with
| Coq_inl _ -> "<reg>"
| Coq_inr id -> extern_atom id in
raise(Type_error (Printf.sprintf "type mismatch in Itailcall(%s): %s"
name msg))
end
| Icond(cond, args, _, _) ->
set_types args (type_of_condition cond)
| Ireturn(optres) ->
begin match optres, retty with
| None, None -> ()
| Some r, Some ty -> set_type r ty
| _, _ -> raise (Type_error "type mismatch in Ireturn")
end
let type_pass1 retty instrs =
List.iter (type_instr retty) instrs
(* Second pass: extract move constraints typeof(r1) = typeof(r2)
and solve them iteratively *)
let rec extract_moves = function
| [] -> []
| Coq_pair(pc, i) :: rem ->
match i with
| Iop(Omove, [r1], r2, _) ->
(r1, r2) :: extract_moves rem
| Iop(Omove, _, _, _) ->
raise (Type_error "wrong Omove")
| _ ->
extract_moves rem
let changed = ref false
let rec solve_moves = function
| [] -> []
| (r1, r2) :: rem ->
match (PTree.get r1 !env, PTree.get r2 !env) with
| Some ty1, Some ty2 ->
if ty1 = ty2
then (changed := true; solve_moves rem)
else raise (Type_error "type mismatch in Omove")
| Some ty1, None ->
env := PTree.set r2 ty1 !env; changed := true; solve_moves rem
| None, Some ty2 ->
env := PTree.set r1 ty2 !env; changed := true; solve_moves rem
| None, None ->
(r1, r2) :: solve_moves rem
let rec iter_solve_moves mvs =
changed := false;
let mvs' = solve_moves mvs in
if !changed then iter_solve_moves mvs'
let type_pass2 instrs =
iter_solve_moves (extract_moves instrs)
let typeof e r =
match PTree.get r e with Some ty -> ty | None -> Tint
let infer_type_environment f instrs =
try
env := PTree.empty;
set_types f.fn_params f.fn_sig.sig_args;
type_pass1 f.fn_sig.sig_res instrs;
type_pass2 instrs;
let e = !env in
env := PTree.empty;
Some(typeof e)
with Type_error msg ->
Printf.eprintf "Error during RTL type inference: %s\n" msg;
None
|
